A resonator can be used to measure mass by detecting the change in resonant frequency by the addition or removal of a small mass on the resonating surface. Resonators are useful, for example, in biological and chemical applications, including samples with a very small mass (e.g., <1 fg). The output of each of the resonators can be digitized using an analog to digital converter (ADC) and the resonant frequency can be determined by an amplitude peak or null.
The conventional approach for measuring chemical or biological samples using oscillating resonators can raise several problems, especially when measuring samples with very small masses. For example, one problem can be the increased measurement time. Long measurement times are undesirable for the user and can introduce errors due to biological (e.g. an ex-vivo sample can degrade or change in time), electrical, environment, material or mechanical changes. Another problem with the conventional approach can be noise. Signals with lower amplitude and higher frequency can be more susceptible to noise.